The object of the invention is a mixed water tap cartridge with thermostatic temperature regulation.
Mixed water taps which serve for the blending of cold and warm water, in which the inflow of the cold water, or of the warm water into the mixing area, is ensured by separate taps, have been known for a long time; these enable the creation of a suitable mixed water temperature between the inflowing cold-, or warm water.
The demand for increased user comfort, brought about the appearance of a mixed water tap which can be operated with a single handle; these appeared from the 1960's onwards with ceramic form-sealing.
These single-handle mixed water taps with ceramic form-sealing have, even after modification, improvement and partial renewal, remained principally identical in structure and function to the original. The relative movement of two ceramics of polished hard surface forming a plan-sealing between each other ensures, through moving only one handle, the regulation of the mixing ratio and flow-through ratio of the cold and warm water. Generally through a vertical movement the opening and closing and through a turning the thermostatic control is ensured. In the aforesaid ceramic disks suitable in- and outflow openings and mixing areas are formed.
This regulating-unit, which contains the two ceramic disks, moving-turning elements, as well as the upper operating-handle, onto which the taps only operating handle is fixed, is as a complete unit, called a cartridge.
Apart from these, other mixed water taps have appeared to meet primarily the needs of medical surgery, ensuring precise outflow water temperature regulation. They are called thermostatic mixed water tap batteries.
Within these water tap batteries two, independent operating elements have been arranged. With the one, the opening and closing of the mixed water flow is achieved. This is traditionally made of a rubber-sealing, or nowadays more commonly a ceramic plane-sealing valve. The other operating element serves the precise setting and regulation of the outflow water temperature.
The function of the latter is based on a precisely calibrated thermal expansion element. The expansion of the heat-expanding element moves a piston, which serves the regulation of the cold and warm water inflow. This piston and the expanding element mounted with it is pressed by the constant force of a spring to the end of a windingly-rising spindle. In the winding spindle a counter-pressure spring of greater force is installed, which in the case of the sudden movement of the temperature regulating spindle (in first line when the temperature turning-knob is set from warm to cold water) ensures that the very low-stroked piston cannot be stretched. The turning-knob can be mounted onto the finely parted ribs on the end of the temperature regulating spindle, into a position in which at the set water temperature (38-40.degree. C.) the corresponding value of the temperature scale is aligned with the base signal.
The temperature scale is generally located on the turning-knob, while the base signal is situated on the housing of the mixed water tap, though it can also occur the other way around. The outflow water temperature of thermostatic mixed water taps remains constant with the value indicated by the temperature scale, independent of temperature, pressure and outflow quantity of the cold and warm water. The cost of a thermostatic mixed water tap battery is much higher than that of single-handle mixed water tap with ceramic disks. The most unfavorable feature of the single-handle mix water tap batteries is that the temperature of the outflow water, apart from the setting of the operating-handle, it is also dependent on the temperature, pressure of the warm and cold water and the set outflow water quantity. This is experienced when in a given angle the fully opened tap is suddenly closed. The outflow water temperature is altered and does not remain constant.
The well known thermostatic mixed water tap batteries also have a number of unfavorable features which cause them to be often defective. One of their greatest disadvantages is that the water outlet opening and closing does not occur through separate cold or rather warm water inlets, but after the thermostatic temperature regulation. As the regulating piston cannot completely close off the cold and warm water branches from each other, the cold and warm water drain systems are in a closed state in connection with each other, and so even the slightest difference in pressure could cause a cross flow between the two branches.
To prevent this from occuring, it is necessary to install a back-flow valve into such mixed water tap batteries at each cold and warm-water induct.
As in such back-flow valves the complete closure could be hindered by even the smallest particle of pollution, it is necessary to install fine sieves in front of the valves. A further disadvantage is the need for two separate and independent regulating units for the water quantity and temperature regulation, which require large, excessive expenditure of material and unconventionally constructed and shaped housings.